Generally a dropped ceiling has crosspiece elements connected at each intersection where they cross by means of grooves, slots, or similar apertures, which extend, respectively, in an opposing sense over approximately half the height of the crosspiece element at hand, and the apertures are spaced in conformity with the layout or grid spacing. When compared with the crosspiece dimensions, large areas are left free between crosspieces. The ceiling also includes suspender devices which can be moved along and in the crosspieces.
The known ceiling systems of this type are comprised of crosspiece elements which are made of strips of chipboard, or similar material which has a surface layer of plastic/synthetic material, and the apertures which serve to join the members at hand are usually furnished at some time after laminating the surface layer of the laminated members or strips.
Such removable ceilings with crosspieces are particularly frequently used in exhibition halls and other similar commerical vending areas. They provide, in conjunction with the lighting arranged at the height of the ceiling, to an optical reduction of the pertaining room height. The region above the suspended ceiling can remain in substantially unfinished condition and may merely be provided with a coating of dark paint so as to be relatively invisible and not to interfere with the general appearance of the room.
The known ceilings are relatively heavy due to being manufactured of chipboard, and they require sturdy suspender or support devices, or a plurality of closely spaced support devices. Such devices are normally composed of two wires or rods, with one being connected to a crosspiece and the other being connected at the ceiling of the structure, and the overlapping ends are held in resilient clamping elements, which elements assist with alignment of the dropped ceiling and adjustment of the crosspiece elements.
For connecting the rods or wires to the crosspiece elements, there are provided grooves, apertures or similar openings in the upper--when in mounted or suspended condition--sides of the crosspiece elements, and brackets which can slide in such grooves are provided in the grooves. The lower ends of the rods or wires of the suspender devices are connected to these brackets.
For safeguarding the relative positions of the crosspiece elements at the intersections where the elements cross, the crosspiece elements are fixed by clamps which are driven into the sides which face in upward direction when the ceiling has been taken down. When arranging such ceilings near the entrance region of sales areas, or the like, an additional optically appealing cover is often desired for the ceiling areas which are embraced by crosspieces. Such covers may include foils or cover plates, and these covers, again, are secured at the crosspieces by means of clamps.
The known ceilings of this type have a substantial disadvantage due to the high risk of crosspieces breaking, particularly at the apertures which take up approximately one-half of the height of a crosspiece and which of necessity are required at the crossings. When mounting or assembling such ceilings, it can normally not be prevented that particularly lengthy crosspieces are broken and rendered useless. On the other hand, longer crosspieces are highly desirable because such ceilings are required for large rooms or halls, and when it is desired to produce a ceiling with relatively few visible abutting locations.
Special problems arise when such ceilings are taken down again and when they are suspended or hung again, either for reasons of adjusting the height in the same location or due to relocation of the ceiling somewhere else, which is frequently the case in exhibition and trade fair halls. When taking down the known ceilings, it is in practice generally not possible to take these down and suspend them at a new location without causing damage. Loosening of the clamps for the crosspieces at the crossings, as well as at any connecting portions between the covers and areas free of covers, is also not feasible without causing damage. In addition, the danger arises that on detachment or similar pulling apart of the securely connected crosspiece elements, breakage occurs, even with only minor tilting or skewing, or the surface coatings are visibly damaged.